一个信号可以连接多个槽函数, 发送一个信号有多个处理动作
一个槽函数可以连接多个信号, 多个不同的信号, 处理动作是相同的
信号可以连接信号
信号函数类
#ifndef ME_H
#define ME_H
#include <QObject>
class me : public QObject
{
Q_OBJECT
public:
explicit me(QObject *parent = nullptr);
signals:
void sendMessage(); //信号函数不需要定义
};
#endif // ME_H
槽函数类：
#ifndef MEPARENT_H
#define MEPARENT_H
#include <QObject>
class meParent : public QObject
{
Q_OBJECT
public:
explicit meParent(QObject *parent = nullptr);
public slots:
void receiveMessage();
};
#endif // MEPARENT_H
#include "meparent.h"
#include "QDebug"
meParent::meParent(QObject *parent) : QObject(parent)
{
}
void meParent::receiveMessage()
{
qDebug()<<"父母接受到消息";
}
#ifndef MYFRIEND_H
#define MYFRIEND_H
#include <QObject>
class myFriend : public QObject
{
Q_OBJECT
public:
explicit myFriend(QObject *parent = nullptr);
public slots:
void receiveMessage();
};
#endif // MYFRIEND_H
#include "myfriend.h"
#include "QDebug"
myFriend::myFriend(QObject *parent) : QObject(parent)
{
}
void myFriend::receiveMessage()
{
qDebug()<<"朋友接受到消息";
}
#ifndef MYTEACHER_H
#define MYTEACHER_H
#include <QObject>
class myTeacher : public QObject
{
Q_OBJECT
public:
explicit myTeacher(QObject *parent = nullptr);
public slots:
void receiveMessage();
};
#endif // MYTEACHER_H
#include "myteacher.h"
#include "QDebug"
myTeacher::myTeacher(QObject *parent) : QObject(parent)
{
}
void myTeacher::receiveMessage()
{
qDebug()<<"老师接受到消息";
}
主窗口中，槽函数和类指针的声明
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include"me.h"
#include"meparent.h"
#include "myfriend.h"
#include "myteacher.h"
#include "ouyang.h"
#include "shinecoln.h"
QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
MainWindow(QWidget *parent = nullptr);
~MainWindow();
me* tom;
meParent* myparent;
myFriend* myfriend;
myTeacher* myteacher;
ouyang* ou;
shinecoln* shine;
//接受按钮信号的槽函数
public slots:
void sendMessage();
private:
Ui::MainWindow *ui;
};
#endif // MAINWINDOW_H
cpp文件如下：
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "QDebug"
MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent)
, ui(new Ui::MainWindow)
{
ui->setupUi(this);
tom = new me(this);
myparent = new meParent(this);
myfriend = new myFriend(this);
myteacher = new myTeacher(this);
ou = new ouyang(this);
shine = new shinecoln(this);
//按钮绑定mainwindow的槽函数
connect(ui->myPushButton,&QPushButton::clicked,this,&MainWindow::sendMessage);
connect(tom,&me::sendMessage,myfriend,&myFriend::receiveMessage);
connect(tom,&me::sendMessage,myparent,&meParent::receiveMessage);
connect(tom,&me::sendMessage,myteacher,&myTeacher::receiveMessage);
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::sendMessage()
{
//qDebug()<<"hello";
tom->sendMessage();
}
消息传递的流程：点击控件，触发主窗口的槽函数。主窗口槽函数调用tom->sendMessage();信号函数，myfriend，myfriend，myfriend同时捕获到信号，按照顺序调用myFriend::receiveMessage meParent::receiveMessage myTeacher::receiveMessage这三个槽函数。
信号类：
#ifndef ME_H
#define ME_H
#include <QObject>
class me : public QObject
{
Q_OBJECT
public:
explicit me(QObject *parent = nullptr);
signals:
void sendMessage(); //信号函数不需要定义
void sendMsg2(QString);
};
#endif // ME_H
#ifndef OUYANG_H
#define OUYANG_H
#include <QObject>
class ouyang : public QObject
{
Q_OBJECT
public:
explicit ouyang(QObject *parent = nullptr);
signals:
void sendMessage(); //信号函数不需要定义
void sendMsg2(QString);
};
#endif // OUYANG_H
#ifndef SHINECOLN_H
#define SHINECOLN_H
#include <QObject>
class shinecoln : public QObject
{
Q_OBJECT
public:
explicit shinecoln(QObject *parent = nullptr);
signals:
void sendMessage(); //信号函数不需要定义
void sendMsg2(QString);
};
#endif // SHINECOLN_H
槽函数类：
#ifndef MEPARENT_H
#define MEPARENT_H
#include <QObject>
class meParent : public QObject
{
Q_OBJECT
public:
explicit meParent(QObject *parent = nullptr);
public slots:
void receiveMessage();
void receiveMsg2(QString msg);
};
#endif // MEPARENT_H
#include "meparent.h"
#include "QDebug"
meParent::meParent(QObject *parent) : QObject(parent)
{
}
void meParent::receiveMessage()
{
qDebug()<<"父母接受到消息";
}
void meParent::receiveMsg2(QString msg)
{
qDebug()<<"父母接受到： "<<msg;
}
ui页面：
头文件：
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include"me.h"
#include"meparent.h"
#include "myfriend.h"
#include "myteacher.h"
#include "ouyang.h"
#include "shinecoln.h"
QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
MainWindow(QWidget *parent = nullptr);
~MainWindow();
me* tom;
meParent* myparent;
myFriend* myfriend;
myTeacher* myteacher;
ouyang* ou;
shinecoln* shine;
//接受按钮信号的槽函数
public slots:
void sendMessage();
void sendMsg2();
void sendMsg3();
void sendMsg4();
private:
Ui::MainWindow *ui;
};
#endif // MAINWINDOW_H
cpp文件：
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "QDebug"
MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent)
, ui(new Ui::MainWindow)
{
ui->setupUi(this);
tom = new me(this);
myparent = new meParent(this);
myfriend = new myFriend(this);
myteacher = new myTeacher(this);
ou = new ouyang(this);
shine = new shinecoln(this);
//一个信号绑定多个槽函数
//按钮绑定mainwindow的槽函数
connect(ui->myPushButton,&QPushButton::clicked,this,&MainWindow::sendMessage);
connect(tom,&me::sendMessage,myfriend,&myFriend::receiveMessage);
connect(tom,&me::sendMessage,myparent,&meParent::receiveMessage);
connect(tom,&me::sendMessage,myteacher,&myTeacher::receiveMessage);
connect(ui->myPushButton2,&QPushButton::clicked,this,&MainWindow::sendMsg2);
connect(ui->myPushButton3,&QPushButton::clicked,this,&MainWindow::sendMsg3);
connect(ui->myPushButton4,&QPushButton::clicked,this,&MainWindow::sendMsg4);
//一个槽函数绑定多个信号
connect(tom,&me::sendMsg2,myparent,&meParent::receiveMsg2);
connect(ou,&ouyang::sendMsg2,myparent,&meParent::receiveMsg2);
connect(shine,&shinecoln::sendMsg2,myparent,&meParent::receiveMsg2);
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::sendMessage()
{
//qDebug()<<"hello";
tom->sendMessage();
}
void MainWindow::sendMsg2()
{
QString s = "tom";
tom->sendMsg2(s);
}
void MainWindow::sendMsg3()
{
QString s = "ou";
ou->sendMsg2(s);
}
void MainWindow::sendMsg4()
{
QString s = "shine";
shine->sendMsg2(s);
}
关键代码：
运行：
信号接收者可以不处理接收的信号, 而是继续发射新的信号，这相当于传递了数据, 并没有对数据进行处理
槽函数的位置不对信号处理，而是对信号的转发。
connect(const QObject *sender, &QObject::signal, const QObject *receiver, &QObject::siganl-new);
例子：
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "QDebug"
MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent)
, ui(new Ui::MainWindow)
{
ui->setupUi(this);
tom = new me(this);
myparent = new meParent(this);
myfriend = new myFriend(this);
myteacher = new myTeacher(this);
ou = new ouyang(this);
shine = new shinecoln(this);
//一个信号绑定多个槽函数
//按钮绑定mainwindow的槽函数
connect(ui->myPushButton,&QPushButton::clicked,this,&MainWindow::sendMessage);
connect(tom,&me::sendMessage,myfriend,&myFriend::receiveMessage);
connect(tom,&me::sendMessage,myparent,&meParent::receiveMessage);
connect(tom,&me::sendMessage,myteacher,&myTeacher::receiveMessage);
connect(ui->myPushButton2,&QPushButton::clicked,this,&MainWindow::sendMsg2);
connect(ui->myPushButton3,&QPushButton::clicked,this,&MainWindow::sendMsg3);
connect(ui->myPushButton4,&QPushButton::clicked,this,&MainWindow::sendMsg4);
//一个槽函数绑定多个信号
connect(tom,&me::sendMsg2,myparent,&meParent::receiveMsg2);
connect(ou,&ouyang::sendMsg2,myparent,&meParent::receiveMsg2);
connect(shine,&shinecoln::sendMsg2,myparent,&meParent::receiveMsg2);
//信号连接信号
connect(ui->myPushButton5,&QPushButton::clicked,tom,&me::sendMessage);
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::sendMessage()
{
//qDebug()<<"hello";
tom->sendMessage();
}
void MainWindow::sendMsg2()
{
QString s = "tom";
tom->sendMsg2(s);
}
void MainWindow::sendMsg3()
{
QString s = "ou";
ou->sendMsg2(s);
}
void MainWindow::sendMsg4()
{
QString s = "shine";
shine->sendMsg2(s);
}
新建的是 myPushButton5 按钮：
//信号连接信号
connect(ui->myPushButton5,&QPushButton::clicked,tom,&me::sendMessage);
信号连接信号（之前都是在mainwindow中建立了槽函数，然后槽函数发送信号）
现在就直接点击按钮，发送信号，然后触发第二个信号me::sendMessage
之前的代码捕获到信号
运行结果为：
